Method of making agitator brushes



Dec. 1, 1942. sw 2,303,800

METHOD OF MAKING AGITATOR BRUSHES Filed Aug. 29, 1940 2 SheetsSheet l INVENTOR EdWa InR. SWann ATTORNEY E. R. SWANN 2,303,800

' METHOD OF MAKING AGITATORBRUSHES Filed Aug. 29, 1940 2 Sheets-Sheet 2 INVENTORV [dwafd swam Q M M ATTORNEY Patented Dec. 1 1942 METHOD OF MAKING AGITATOR BRUSHES Edward R. Swann, North Canton, Ohio, assignor to The Hoover Company, North Canton, Ohio, a

corporation of Ohio Application August 29, 1940, Serial No. 354,644

10 Claims.

The present invention relates to a method of making an agitator brush for suction cleaners. More specifically, the invention comprisesan improved method of making an agitator brush for a suction cleaner by the use of a continuous source of bristles which are fed into a mold and imbedded in a thermoplastic material.

It is an object of the present invention to provide a new and improved method of making a surface-coyering-agitating brush for asuction cleaner rotary agitator. ,Ano'ther object of the invention is to provide a method for makingagitator brushes by molding a back of thermoplastic material to synthetic organic brush bristles.

.Still another object of the invention is to provide a method of making agitating brushes for rotary agitators for suction cleaners by the use 'of bristles from a continuous source which are advanced step by step into an injection-mold to be imbedded in a thermoplastic brush back and thereafter cut to length. These and other more specific objects .will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawings'towhich they relate.

Referring new to the drawings in which a I preferred embodiment of the present inventio is disclosed? u Figure 1 is a front view of a suction cleaner with a portion of the front nozzle wall broken away to show a rotary agitator positioned therein which incorporates a brush unit constructed in accordance with the present invention;

Figure 2 is a view in perspective of a section of the removable brush unit constructed in accordance with the present invention;

Figure 3 is a side view of the end of a strand of brush bristles from a continuous source;

Figure 4 is a view similar to Figure 3 and illustrates the same strand of filaments with the outer end bonded together by heat in order that the strand can be threaded into the mold; Figure 5=is a partial view in perspective of the movables'ection of the mold with brush tufts threade'd'finto some of the tuft seats, certain of the tufts 'beingI-"jeut to proper lengthafter insertion'; r Figure 6 is a -partial longitudinal section through the mold i nizclosed position *an'd illustrate's the plurality of tufts extendedw li'ntdthe brush back cavityawait-ing the inject 'n of the back material; U a

Figure? is'ai transverse section through the mold upon the line 7-1 of Figure 6' and shows the injection nozzle in place and the mold cavity being filled with the back materialin a molten or plastic condition; I

Figure 8 is a section upon the line 8-8 of Figure 6, but with the mold in an open position.

and discloses the opening operation of the mold with the movable mold tection sliding along the brush tuft strands befor e the ejection pins have forced the brush back from its cavity;

Figure 9 is a view of the last step of the operation in which the movable section of the mold;

as illustrated in Figure 8, has moved to open position, the brush back has been ejected by the V ejection pins from the brush back cavity, and the brush tufts are being cut'to length.

The modern suction cleaner embodies surface brushing and beating means which cooperate with a flow of cleaning air in the removal of foreign material from the surface covering undergoing cleaning. Surface brushing and beating means preferably comprise a rotary agitator which incorporates rigid surface beating elements and flexible surface brushing or sweeping elements. The beating elements function to vibrate the surface covering to effect the dislodgment therefrom of foreign material imbedded therein while the brushing elements perform 2. pile straightening and smoothing function and,

to a limited extent dependent upon the flexibility of the elements, a vibrating-and dirt dislodging effect. It has been found that filaments of certain synthetic organic compounds can be used as brush bristles which function satisfactorily in place of the usual animal hair bristles in the agitator brush unit. In the present invention bristles made of synthetic organic compounds are molded into a base of thermoplastic material by an improved method in which the brushtufts are fed from a continuous source into the brush back cavity of the mold to be engaged by the thermoplastic brush material'and thereafter cut to length, the brush tuft material and the ,brush back material being so selected that fusion takes place in the molding operation to produce a bond whichis stronger than a mere mechani-' ing fan 3 carried by the downwardly extending lower end of the motor shaft 4. A motor casing 5 is positioned immediately above the main casing l and houses an unshown driving'motorof any ordinary type and Which includes ,the shaft 4. The entire cleaner body is movably supported l is positioned a rotatably mounted cylindrical agitator Ill upon the surface of" which: are positioned helically extending rigid 'beaterbars ll..

Within recesses l2 in agitator,ll areirpositioned elongated brush-units or elements comprising rigid backs l3 and tufts of bristles 44, the brushes being removably secured by means of screws IS. The brushes are illustrated as beingv axially extending but can as well extend in curves, if desired, around the agitator. The agitator is rotated by means of power-transmitting belt l6 which seats in a grooved pulley ll formed centrally in the agitator body. Power to the belt is provided by the motor shaft 4.'

Referring now to Figure 2 in particular, an enlarged view of the brush elements per se is shown. The brush base or back I3 is seen to be formed along its side with laterally extending shoulders 20, 2G,.between which is a longitudinally extending recess or groove 2|. In each end of the brush back is a vertically 'extending screw-receiving seat 22 adapted toseat the screws I illustrated in Figure 1. Extended vertically from the back along the longitudinally extended groove 2| is a line or seriesofbrush tufts l4. Each of these tufts comprises a plurality of bristles, each of which, extends downwardly into the back l3 in which 'it is fixed.

The bristles are 'not looped andj-therejare no brush tuft seats which can' be independently identified as such. are positioned in the brush back and are individually enclosed by and in fact fused with the material of the brush back. a

In a preferred embodiment, the brush bristles are formed ofnylon, a synthetic'organic compound which is also identified as a synthetic linear condensation polyamide' and also as a synthetic fiber-forming polymeric amide;

conjunction of the bristles andfthejback, which fusion provides a, permanent bond stronger thana mere mechanical bond.

Referring now to Figures 3 1:09, inclusive, the L proposed: method of making the .brush element The brush back is known as vinylite, which is iden-' tifiable as a polymer vinyl acetate and vinyl Y in Figure 6.

Instead the brush bristles fill in accordance with the present invention is illustrated. A plurality of filaments of a synthetic organic compound, such as nylon, are brought 1 together to form a continuous strand which' may be gathered in the form of a skein or wound upon a drum. An end of such a strand is illustrated in Figure 3. The number of such strands used is dependent upon the number of brush tufts which are to be formed'in the individual brush unit. Reference to Figure .2 illustrates that the brush tufts are positioned side by side and are contiguous. Their number will depend upon the length of .the brush back. The end of each brush tuft strand is subjected to a heat treatment, which may be eitherexposure to high temperature or direct exposure for a very brief interval to-a flame for the purpose of forming a bond between the separate filaments of the strand may be threaded into the tuft seat in the mold. as illustrated in Figure 5.

In Figure 5 the brush tuft strands, indicated by the reference character 24, are shown threaded into tuft seats 25 formed in the movable mold section 25. Two of the tuft strands are there illustrated immediately after insertion with the fused outer ends thereof in place. All of the tufts are, after being fed into the mold section 26, cutoff, as illustrated by the two shorter tuft sections in Figure 5, so that they protrude a distance beyond the mold section 26 which is cqual to the distance which the brush tufts are to be imbedded in the brush backs. The flexible conduits 21 convey cooling fluid to the mold section 26.

After the placing of all the tuft strands in the mold section 26, the latter advances to the stationary mold section 30, illustrated in Figures 6 to 9. inclusive, which section is formed with the brush back cavity. A feeding inlet 32 extends from the back of the mold section 30 into the cavity and is adapted to convey the plastic material for the brush back to the cavity from the injection nozzle 33, illustrated in Figures '7 and 9. Ejector pins 34 are slidingly mounted in section'30 and are adapted to be propelled inwardly at the conclusion of the molding operation to eject the brush back from the cavity 3|.

With the movable mold section 26 advanced into place relative to the stationary section 30 the strands 24' are extended beyond the section 26 and into the cavity 3| as is clearly illustrated Upon sealing contact being made between the two mold sections the material of the brush back l3 is injected from the nozzle 33 through the inlet 32 completely filling the cavity 3| and coming into contact with each separate filament of each brush tuft strand. 24. The back material l3 which, as stated above, is preferably of vinylite, is heated into a plastic condition and upon contact with the ends of the brush tufts fusion takes place therebetween. Eacnof the mold sections is provided with a plurality of 'conduits'36 which are fed by a cooling fluid which circulates through the mold the fluid formovable section 26 coming from the flexible conduits 21. Two of these orifices, conduits or passageways 36 in the movable section 26 of the mold are positioned along and immediately adjacent the brush tuft seats 25 and perform a cooling function which reduces the temperature of the tuft strands and, of course, the temperature of the mold at that point. This results in a lowering of the temperature of the plastic back material which solidifies and is not extruded along the strand into the seat 25. This is desirable as any such extrusion results in a brush tuft strands 24 being held in the newly formed back which is temporarily stuck in the mold cavity, have passed along the tuft seats 25 in each instance as the mold section moved- The distance of this movement is indicated by the strand, as illustrated in Figure 4, so that the characters a: plus y and is a distance which is equal to the brush tuft length or height a; in the completed'brush unit plus a distance 1/ which is mold sectionfhaving. may,

' action and fore the brushiback lg I .31, the backQ l3 carry g thereafter be] rem such asflfiling. orecu a 4 movement 'of"the movable,mold section,26 be-a. advancing a feeder to feed a strand of organic bristlesinto a stationary mold shaped'to form a {:brush back, .;'injecting a heated thermoplastic equal er hs, i -ante. whiskin -$11 M; imbeddedin' the brushpa ..-,U pon'the; ovable iy t ltz his s i tance' .2: plus the v,

w d s Pl s 1 llustrated-in Fi ureB, to its outermost position, illustrated in Figure 9, is accompanied by a corresponding movement of the newly formed brush unit which is still connected thereto by the tuft strands 24. Upon the mold section 26 reaching its outermost position, two cooperating knife blades Y38 and 39 contact the opposite sides of the aligned filament strands to sever them, as is clearly illustrated in Figure 9, and the newly formed brush unit falls,

as is also illustrated in Figure 9, into a suitable receptacle or catch receiver. moved in any suitable manner and the newly formed brush is ready for use. The operation of forming the next; brush unit is immediately begun with the advance of the movable mold section 26 toward the stationary section; The

operation. is, of course, a repetition of that described.

. It is to be understood that thegprotection herein applied for is notconl'ined to h p r ul r combinations of features orelement's set ',out"in the following claims: Protection. israherein; ap-

a v 0 injecting a heated thermoplastic into said mold plied for, for any one-or more of' the features or elements referred toin thefollowingclaims;or ;,5 described in the foregoing "specifications orshqwn J in the accompanying drawings, either independe ently or in combination.

I claim:

1. The method of making a brush comprising 40 loading a movable mold section with brush bristles so that the bristles extend therethrough and therefrom, advancing the saidzimoldsection and said bristles into cooperating position with a second mold section formed with a brush back cavity which encloses the projecting ends of said brush bristles, injecting a, heated thermoplastic into said cavity to form a brush back in whichsaid bristlesbecome embedded, retracting said movable mold section from said cooperating position while said bristles remain stationary, eject ing said back from said cavity, and cutting said bristles to length.

2. In a method of making a brush, the steps comprising feeding, a plurality of continuous cavity to form a back'in which said bristles become embedded and fixed, and retracting said movable mold section from said stationary mold section and without moving said bristles a distance equal to the desired bristle length plus the The sprue is restrands .becomeeinbedded, separating said movble,iand-.-said;second,mold section a distance at a as great as the desired length of bristle or, said;brush, said movablemold section sliding vensaid strands in said separation, cutting said lstrandsito form-brush. tufts carried by said back, andgejecting said; back from said second moldeQtiQD-zaa' 4-.--: In a method of making a brush, the step of from a stationary source into said mold to form a back and to anchor said bristles, retracting said feeder a distance equal at least to the desired length of brush tuft with said bristle and back remaining fixed, and severing said strand between said back and said feeder.

5. In a method of making a brush, the step of advancing a feeder to feed a strand of organic bristles into a stationary mold shaped to form a brush back, injecting a heated thermoplastic into said mold to form a back and to anchor said bristlesyretracting said feeder a distance at least equal to the desired length of bristle for said brush plus a distance equal to the length of I bristle embedded in said back and with said bristle and back remaining stationary, and severing said strand. at a I distance from said back equal to thefdesired length of bristle.

61111 a method of making a brush, the step of advancing a feeder to feed a strand of organic bristles into a mold shaped to form a brush back,

to form a back and to anchor said bristles, cooling said bristlesand said thermoplastic adjacent said bristles to prevent extension of the latter along the former, retracting said feeder a distance equal at 'least'to' the desired length of brush tuft, and

severing sald strand between said back and said feeder.

' '7. In a brush making machine, a stationary mold section formed with a brush back cavity, a reciprocatory mold section formed with friction bristle seats adapted to retain releasably by frictional engagement a bristle extended therethrough, cooling orifices in said movable mold section to cool bristles positioned therein and to prevent extrusion of material into said seats, and means to inject a molten material into said cavity in said stationary mold section. i

8. In a brush making machine. a stationary mold section formed with a brush back cavity, a reciprocatory mold section formed with friction bristle seats adapted to retain releasably by frictional engagement a bristle positioned therein, cooling orifices in said movable mold section to cool bristles positioned in said movable sectionand also in said stationary section adjacent' thereto to prevent extrusion of material into said seats, means to inject a molten material into said cavity in said stationary mold section, means to eject a back from said cavity in said stationary mold, and means to cut said distance said bristles extend into said back, and 5 bristles lengthsevering said bristles at said latter distance from 1 9. In a brush making machine, a Stationary aid movable m ld, j mold section formed with a brush back cavity,

3, I th d of making a brush, t steps a reciprocatory mold section adapted to be reof feeding a plurality of brush strands compo ciprocated toward and'from said stationary mold of a multiplicity of filaments into a brush back 0 section and formed with a ality of brush cavity in a second mold section by means of a movable mold section through which the strands extend individually, injecting a molten brushback-forming material through said second mold into said cavity to form a back in which said bristle seats extended entirely therethrough and opening into said cavity with said sections juxtapositioned, said seats being of a size to engage frictionally the brush bristles positioned therein, means to inject moldable material through said stationary mold into said cavity-to'form' a brush back about the --:EI1HS. .-Of the-:brlstles 1 extended therein, means acting through saidstationary mold section to elect a molded brush back therefrom-to permit the newly formed-'brush unlt' to be carried by theabristlessina'said' recipiocatory mold section; and means tocutthe bristles-at a equal to thedistance 10. The method of distance from the face of said reciprocatry mold said bristle's areembedded in said back. r,

aking a brush comprising tufts of bristles-forwardly feeding a plurality o1 until their ends extend into a brush back cavity formed'in a stationary mold, molding a brush back aroundthe ends of said bristles, retracting embeddd in saidback plus a distance equal to -the desired bristle extension above said. back,-

- ejec'tihgsaid back from its mold thereby leaving it supported by said bristles, and severing said bristles at a distance from said back equal to the desired bristle extension'from said back.

EDWARD R. SWANN.

CERTIFICATE 013' CO RRECTI ON Patent N6. 2,505, 00. -December 1', 191 2.

EDWARD 13. SWANN.

It is hereby certified that error apnears in the. printed specification of the above numbered patent requiring correction as follows: 'Page 5, sec- 0nd column, line 58, claim 6, after the word ."feeder" insert --along said line 59, same claim, after tuft and. before the comma insert bristles--; with said back and bristles remaining stationery"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. Signed and sealed this 50th day of March, A. D. 1910.

Henry Van Arsdale,

(Seal) Acting Commissioner of Platerits, I 

